How can I create a list Array (the list display First Alphabet when scroll) with the cursor data?
5 Answers
Go through every element in the Cursor, and add them one by one to the ArrayList.
ArrayList<WhateverTypeYouWant> mArrayList = new ArrayList<WhateverTypeYouWant>();
for(mCursor.moveToFirst(); !mCursor.isAfterLast(); mCursor.moveToNext()) {
// The Cursor is now set to the right position
mArrayList.add(mCursor.getWhateverTypeYouWant(WHATEVER_COLUMN_INDEX_YOU_WANT));
}
(replace WhateverTypeYouWant with whatever type you want to make a ArrayList of, and WHATEVER_COLUMN_INDEX_YOU_WANT with the column index of the value you want to get from the cursor.)
4 Comments
Dennie
Hi, The important thing I want to do is display "Fist character" in my List. After I get all data from cursor, I don't know how to convert it to an String[] Array to get "First character". It look something like this char firstLetter = mString[firstVisibleItem].charAt(0);
Javier Sedano
Friends: the for loop above is not completly right (condition and increment anre swapped). Use
for(mCursor.moveToFirst(); !mCursor.isAfterLast(); mCursor.moveToNext()) {}
WarrenFaith
This type of loop is kind of awful to read. The solution from @PearsonArtPhoto is way more elegant and easier to read.
IgorGanapolsky
What do you mean by getWhateverTypeYouWant? Is that a real method.
One quick correction: the for loop above skips the first element of the cursor. To include the first element, use this:
ArrayList<String> mArrayList = new ArrayList<String>();
mCursor.moveToFirst();
while(!mCursor.isAfterLast()) {
mArrayList.add(mCursor.getString(mCursor.getColumnIndex(dbAdapter.KEY_NAME))); //add the item
mCursor.moveToNext();
}
2 Comments
DonnaLea
very good point imbrizi. This is a much better way to loop through the elements of the Cursor
Pratik Butani
how to add two or more column value??
Even better than @imbrizi's answer is this:
ArrayList<String> mArrayList = new ArrayList<String>();
while(mCursor.moveToNext()) {
mArrayList.add(mCursor.getString(mCursor.getColumnIndex(dbAdapter.KEY_NAME))); //add the item
}
moveToNext() will return false if there isn't anything left, so this reduces the SLOC by a few, and is easier to see.
Even better is to get the column index outside of the loop.
ArrayList<String> mArrayList = new ArrayList<String>();
int columnIndex=mCursor.getColumnIndex(dbAdapter.KEY_NAME)
while(mCursor.moveToNext()) {
mArrayList.add(mCursor.getString(columnIndex)); //add the item
}
This one worked really well for me because I wanted an arraylist of objects:
List<MyObject> myList = new ArrayList<String>();
Cursor c = ...
while(c.moveToNext()) {
myList.add(new MyObject(cursor.getInt(cursor.getColumnIndex("_id")), cursor.getString(cursor.getColumnIndex("column1")), cursor.getInt(cursor.getColumnIndex("column2")));
}
c.close();
Just make a POJO MyObject and make sure it has a constructor.
Comments
In Kotlin you can use this extension:
fun <T> Cursor.toList(block: (Cursor) -> T) : List<T> {
return mutableListOf<T>().also { list ->
if (moveToFirst()) {
do {
list.add(block.invoke(this))
} while (moveToNext())
}
}
}
and use it:
val listOfIds = cursor.toList {
// create item from cursor. For example get id:
it.getLong(it.getColumnIndex("_id"))
}
ArrayListwith the data of a cursor?